Carbon nanotubes (CNTs) are the promising candidate as cold cathode materials for field emission displays (FEDs). A CNT FED can be fabricated with low-cost printing techniques, which will be very competitive to current types of flat panel displays, such as liquid crystal displays (LCDs) and plasma display panels (PDPs). Cathode uniformity is a critical factor for commercializing CNT FEDs. The main issues related to field emission uniformity are the uniform dispersion of CNTs, physical size uniformity of CNT pixels, and activation uniformity of the cathodes because most of the printed CNT cathode is required to be activated with various methods including adhesive tape, roller, sand blasting, etc. The activation process can raise the CNTs upward or free the CNTs from binder materials to make them stand upward in response to an applied electrical field.
On the other hand, for CNT cathodes deposited in tens of micrometers deep cavities for triode structures, the current activation processes will not have the same uniform activation effect as on CNT cathodes on a flat surface. To have uniform activation, the uniform pressure and physically uniform contact to the surface of CNT cathodes from the activation materials are very important to obtain uniform field emission cathodes. But due to the deep cavities of triode structures, the activation materials may not uniformly touch the surfaces of the CNT cathodes with the same pressure, resulting in non-uniformity of field emission.